<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <div id="app">
        <p>one</p>
        <p id="two">two</p>
        <button id="btn">删除</button>
    </div>
    <script>
        var app = document.getElementById("app");
        var two = document.getElementById("two");
        var btn = document.getElementById("btn");
        btn.onclick = function(){
            // app.removeChild(two);
            two.remove();
        }
    </script>
</body>
</html>